1. Field of the Invention
This invention relates to color television cameras using solid-state photosensitive arrays. In a primary application the invention relates to CCD color television cameras where a plurality of horizontal lines are read out simultaneously to provide the required color information.
2. Description of Prior Art
In recent years solid state color television cameras have begun to replace the cameras using one or more camera tubes. The advantages of the solid state cameras are numerous including small size, light weight, geometric accuracy and eventual reduced cost.
For the most part, the solid state camera systems have followed the general design of those using camera tubes. These systems can be separated into the categories of single-tube encoded color cameras, which are prevelant in the consumer market, and multiple tube color cameras, which are prevelant in the broadcast market. The single tube systems generally employ colored striped grating patterns for encoding the color information. Since these color carriers should not interfere with the luminance information, they generally are at relatively high spatial frequencies, making them difficult to resolve. The multiple tube color cameras generally employ complex optical systems for splitting the images into its component colors and imaging each color onto a different camera tube. These optical systems result in considerable light losses and registration problems. Hubrid systems have been used such as a two camera tube system with a luminance camera tube and an encoded-color camera tube.
Unfortunately solid state cameras, such as those using CCD's, have continued to use these same approaches. This is clearly set forth in a recent paper in the September, 1979 issue of Electro-Optical Systems Design by R. L. Rodgers III entitled, "Prototype CCD Color Television Camera." This paper explores the two systems. The single CCD color camera requires significant additional resolution to resolve the high frequency color gratings. These gratings must have a periodicity at the edge or beyond that of the luminance bandwidth to prevent interference with the luminance signal. On the other hand the multiple-device CCD system has a complex optical system with light loss and registration considerations. The geometric accuracy of the CCD's themselves minimizes the registration problem although the optical system continues to have significant registration problems. Also, the multiple device CCD systems have the obvious problem of high cost as do the very high-resolution single CCD devices. Another description of a system using three separate CCD camera devices is given in U.S. Pat. No. 4,007,488 issued to M. Morisheta, et al.